Spotlight Cam Plus connected, but no recording or live view

I recently installed a 5 camera Ring system at a relative's house consisting of 4 wired Spotlight Cam Plus and a doorbell. This setup worked very well for a few weeks, after which 3 of the spotlight cams stopped showing video. One of them was showing offline (of the 5 cameras it was the one I thought *might* have signal issues over time due to placement) but the other 2 showed online with sufficient signal strength. These would also register events, however the app would say the footage was unavailable. Live view would not work (said that the camera was not connected even though it was) and light/siren triggers would not work through the app. I revisited the site and did as much on-site troubleshooting as I could and could never get the 3 cameras in question to work, even after moving them as close to the router as I could (relatives were out of town so I couldn't get inside). I was able to get image at one key location by moving the one spotlight model that was still working from the back of the house to the front. The doorbell has never given an issue. I removed the 3 cameras in question and brought them home so I could work on them on a bench and can still not get them to operate correctly. I reset them sucessfully and remove them from the app. I can get through the setup process as well....scan the barcode, trigger setup mode with the top button and the process will finish. The cams will immediately go into update mode, but once that finishes they just stop functioning. They show connected with strong signal (router is in the same room) but no live view and no motion trigger events registering. One of the units seems to be stuck in an update loop. It'll update (shows in the app and via flashing light on the cam) then a while later it's doing it again. I can only figure the cameras are defective, but not being very experienced with Ring products I wanted to ask here. It seems that there have been a good many reports of this type of issue, but I haven't seen a clear resolution.